B18B Burnt Exhaust Valve Problem

I completed a compression test which showed that cylinders 1,3, and 4 had compression of 180psi and cylinder number 2 had a low compression reading of 150

Upon disassembling and removing my b18b cylinder head, i noticed that 2 exhaust valves on one cylinder (number 2) were of an off white colour compared to all the other valves being a charcoal colour, and also the piston in this cylinder (number 2) is dry compared to the other pistons as show in the picture also.

I'm unsure what has caused this problem and what will need to be fixed/ replaced to fix the problem

yeahh the oil control rings were gummed up so that might have been part of the problem, i think it might be that the cylinder was running lean as the injectors where badly carboned up
how will the car running rich cause this problem? as i also suspect the car might be running rich as its using alot of fuel